UIWebView and Gesture Detection
Introduction
In this article, we will explore how to detect gestures on UIWebView in a View-based iOS application. Specifically, we will look at the differences between using UIWebView and WKWebView, as well as how to implement tap detection on these web views.
Background
When it comes to displaying web content in an iOS app, there are two primary options: UIWebView and WKWebView. Both of these classes provide a way to display HTML content, but they have different approaches to gesture recognition.
UIWebView uses a traditional web view engine, which is the same one used by Safari. This means that any gestures detected on the web view are handled by the system, rather than being handled by your app’s code. This can make it more difficult to implement custom tap detection.
On the other hand, WKWebView provides a more modern and powerful way of displaying web content. It uses a new engine called WebKit2, which allows for more fine-grained control over gesture recognition. With WKWebView, you can detect taps on the web view using the WKNavigationDelegate protocol.
In this article, we will focus on implementing tap detection on WKWebView.
Detecting Taps with WKWebView
To implement tap detection on WKWebView, you need to conform to the WKNavigationDelegate protocol. This protocol provides a method called webView(_:shouldBeginNavigation:), which is called whenever the user taps on the web view.
Here is an example of how to use this method to detect taps:
import UIKit
import WebKit
class ViewController: UIViewController, WKNavigationDelegate {
let webView = WKWebView()
override func viewDidLoad() {
super.viewDidLoad()
webView.delegate = self
// Add your HTML content here
webView.loadHTMLString("<html><body><button>Tap me!</button></body></html>", nil)
}
func webView(_ webView: WKWebView, shouldBegin navigationAction: WKNavigationAction, predictionController: UIViewControllerPredictionController?, completionHandler: @escaping (Bool) -> Void) {
if let url = navigationAction.url {
if url.path == "/tap" {
// Handle tap
print("Tap detected!")
}
}
completionHandler(true)
}
}
In this example, we create a WKWebView instance and set its delegate to our view controller. We then load some HTML content into the web view.
When the user taps on the “Tap me!” button, the shouldBegin method is called with the navigation action’s URL. If the URL path matches “/tap”, we handle the tap by printing a message to the console.
Implementing Tap Detection in the MainWindow.xib File
As mentioned in the original question, it’s also important to ensure that your main window is of type TapDetectingWindow and not UIWindow. This is because UIWindow does not support gesture recognition by default.
To fix this, you can use a hack where you create a custom subclass of UIApplication that sets the window type:
import UIKit
class TapDetectingApplication: UIApplication {
override class func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Create a custom window type
let tapDetectingWindow = UIWindow(frame: UIScreen.main.bounds)
tapDetectingWindow.windowType = .tapDetecting
return super.application(application, didFinishLaunchingWithOptions: launchOptions)
}
}
class AppDelegate: NSObject,UIApplicationDelegate {
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Set the window type to tap detecting
TapDetectingApplication.shared.windowType = .tapDetecting
return super.application(application, didFinishLaunchingWithOptions: launchOptions)
}
}
In this example, we create a custom subclass of UIApplication that sets the window type when the app launches. We then set the window type in our delegate’s application method.
Conclusion
Detecting gestures on UIWebView requires some additional setup and configuration compared to using WKWebView. However, with the right approach, you can implement tap detection on these web views and provide a more interactive experience for your users.
In this article, we explored how to detect taps on WKWebView using the WKNavigationDelegate protocol and implemented tap detection in the main window’s xib file. We also covered some common gotchas when working with UIWebView and WKWebView.
By following the steps outlined in this article, you should be able to implement tap detection on your own View-based iOS app that uses a web view.
Last modified on 2023-11-29